| Biomass refers to the variety of organisms through photosynthesis, including all of the animals and plants and microorganisms. And so-called biomass energy, is the form of solar energy in the form of chemical energy stored in the biomass, that is take biomass as the carrier of energy. Now many countries are actively research and development and utilization of biomass energy, which usually includes wood, forest waste, aquatic plants, oil plants, urban and industrial organic waste, animal waste, etc. Biomass energy of the earth’s resources is relatively abundant and which is the energy of harmless. People pay attention to the advantages of biomass, but at the same time, they should also pay attention to the biomass itself emission of VOCs and biomass burning emission of organic matters impact on the environment.This paper based on levoglucosan and dehydroabietic acid as typical tracer molecules released by the biomass combustion and monoterpene (ocimene, myrcene, linalool) emission by biomass as the representative for research, using high level quantum chemical density functional theoretical method study and analysis their oxidation degradation mechanism in the atmosphere at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. And to calculated the related dynamic datas by using the Rice-Ramsperger-Kassel-Marcus(RRKM) theory. The detailed mechanism has lead to the following conclusions:1. The atmospheric oxidation degradation mechanism and kinetics properties of levoglucosanThis paper adopts the method of high-precision quantum chemical to study all the important reactions between levoglucosan and OH radical. The OH-initiated reaction of levoglucosan is one of the main eliminating ways. The possible subsequent reactions in the presence of O2, NO and H2O are also taken into consideration. The study shows that the H atom abstraction from the C4-position by the OH radical is an energetically favorable pathway, and the OH-initiated products contribute to the formation of SOA and atmospheric acidity. The rate constant of levoglucosan reacting with the OH radical at298K is2.21×10-13cm3molecule-1s-1and the atmospheric lifetime is26days ([·OH]=2.0×106molecule cm-3).2. The atmospheric oxidation degradation mechanism and kinetics properties of dehydroabietic acidIn this paper, the atmospheric mechanism of DHAA initiated by OH radicals and O3was studied at the MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level. For OH-initaited reaction with DHAA, both OH-addition reactions and H-abstraction reactions are significant. The result of RRKM kinetic calculation shows thatthe rate constant of OH radicals with DHAA is8.9×10-12cm3molecule-1s-1at298K and under the pressure of760Torr. The rate constant of OH addition reaction is2.00×10-12cm3molecule-1s-1, while that of the H atom abstraction is6.89×10-12cm3molecule-1s-1. The O3addition to the aromatic ring of DHAA is vital to the atmospheric reactions, because the concentration of ozone is high in the troposphere and the ozone can participate in atmospheric reactions all day. And the rate constant of O3reacting with DHAA is2.29×10-20cm3molecule-1s-1.3. The atmospheric oxidation degradation mechanism and kinetics properties of monoterpeneIn this paper, we studied the oxidation degradation reactions between ocimene, myrcene, linalool and ozone, respectively. And we discussed the secondary reaction in the presence of O2, NO and H2O. It also studies the reaction trend in the liquid phase. At298K, the rate constant of ocimene, myrcene, linalool are7.19×10-16,3.51×10-19and3.83×10-16cm3molecule-1s-10... |
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